Most data processing systems include a plurality of peripheral devices which must be controlled to perform certain operations at certain times or in certain sequences. Control of these peripheral devices in accordance with the requirements of the data processing system can be accomplished in various ways. Frequently, microprocessors have been used for this purpose in the past. One disadvantage to the use of microprocessors for this purpose in small systems is that they provide a relatively expensive control means, and another disadvantage is that they are often relatively slow, due to the large number of cycles of operation which a typical microprocessor requires for performing a series of sequential operations.
A need therefore exists for a data processing device capable of controlling peripheral equipment or processes not requiring either arithmetic or the power of a microprocessor, but having control requirements which are sequential in nature and which are sufficiently complex in character to require an extensive array of small and medium scale integrated circuits.